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  1. K

    Energy of system involving pressurized gas

    Homework Statement I am doing a project where I will be using a pressurized PVC pipe to lob a beanbag over a barrier and onto a ground target. Like a potato cannon, 1 chamber will have ~ 6.5 atm absolute pressure and when a valve is released, gas will flow along the pressure gradient into a...
  2. K

    Know where to find any Quantum Mechanics practice problems?

    Also, if anybody else is looking too, here are some resources I've dug up: http://lanl.arxiv.org/abs/physics/0004072 Found this on physicsforums, tons of notes on QM and a few examples for each topic http://mini-me.chem.uh.edu/pchem07/page0/page17/page17.html -Professor put 17 of his old QM...
  3. K

    Know where to find any Quantum Mechanics practice problems?

    I have a Quantum Mechanics test on Wednesday and I was wondering if someone could recommend somewhere for me to find some practice problems and answers. I've googled and found some practice tests, but they don't have any answers for me to make sure I'm doing them right. The book I have is...
  4. K

    (very) nonstandard reduction potential

    It is 10^-6! That little typo caused me all kinds of headache. Also, your balanced half reaction is exactly how I would have done it too, but the one above was provided by my professor and is a valid half cell reaction. I'm not exactly sure why it is that way, but I double checked on...
  5. K

    (very) nonstandard reduction potential

    I have a question that I am familiar with, but there is no answer provided and about 1000 ways to make small mistakes. I was hoping someone could take a glance and see if any mistakes jump out. Any tips would really be appreciated. Question What is the reduction potential required for reducing...
  6. K

    Oxidation #'s in [Re2Cl9]2-

    Ok, finally figured it out above. I am trying to balance this equation, and in order to break it into half reactions, I need to know the ox #'s of each atom to see which is the reduction half and which is the ox half. If the Re is 3.5 like you say, then am I on the right track that the...
  7. K

    Oxidation #'s in [Re2Cl9]2-

    {ReCl}_5} + {{H_2}O} --> {Re_2}{Cl_9}^{2-} + {ReO_4^-} + {Cl^-} + {H^+}
  8. K

    Oxidation #'s in [Re2Cl9]2-

    Ok, I'll test it by quoting someone that used it sucessfully. ^{33}_{17}Cl^{16}\xrightarrow{n,n}~^{31}_{15}P^{16 }+~^4_2He^2
  9. K

    Oxidation #'s in [Re2Cl9]2-

    Sorry about no latex, when I try using latex my formulas just wind up as a link that says "LaTeX graphic is being generated. Reload this page in a moment." Anyway, I was trying to balance a redox equation and I am completely stumped as to how: [Re2Cl9]^2- can be possible. I'm...
  10. K

    Statistics question

    I have some statistics on a test from my biology class and I was wondering if there is enough information provided by the stats to be able to calculate the average of the top 5% of scores. I have used a graph in mathematica to get a pretty good idea of what the top 5% average is, but I was...
  11. K

    Frequency for ionization of hydrogen

    Homework Statement Does an AM radio station broadcasting at 750 KHz emit enough energy to ionize a hydrogen atom? Homework Equations Frequency = 7.5E+5 /s Ionization E of H atom = 2.18E-18 J Planck constant h = 6.625E-34 J-s AM Radio speed = c Energy AM radio wave = h*frequency...
  12. K

    Phase shift from path difference

    1. Homework Statement A wave front moving horizontally encounters a block of glass that has an index of refraction of 1.50 in its upper half and an index of refraction of 1.25 in its lower half. The wavelength of the wave front in air is 700 nm. At what lengths would the glass block cause...
  13. K

    Phase shifted waves due to path difference

    Homework Statement A wave front moving horizontally encounters a block of glass that has an index of refraction of 1.50 in its upper half and an index of refraction of 1.25 in its lower half. The wavelength of the wave front in air is 700 nm. At what lengths would the glass block cause...
  14. K

    Interference fringes with reflected light

    You just made me slap my forehead! Thank you kindly for pointing out the obvious :)
  15. K

    Interference fringes with reflected light

    Well, I made a diagram: I thought it might help, but I still haven't even figured out where to start.
  16. K

    Interference fringes with reflected light

    Homework Statement A point source of light (λ = 589 nm) is placed 0.4 mm above the surface of a glass mirror. Interference fringes are observed on a screen 6m away, and the interference is coming from light reflecting off the mirror and light coming directly from the source. Find the...
  17. K

    Interference question

    Maybe this picture will help: Phase difference at point P will be: pi + (a + b)(2 pi) / wavelength Maybe I need to find a function that gives the phase shift at point P in terms of (a + b)...not sure though
  18. K

    Interference question

    I was under the impression their path difference would only be 0.4mm for the light ray reflecting off the mirror directly behind the light source.
  19. K

    Interference question

    I just found that mirrors do cause a phase change of pi, but I still can't figure out how to relate path difference to the fringes on the screen
  20. K

    Interference question

    I have run into a problem and I haven't been able to even begin figuring it out: A point source of light with wavelength 589 nm is placed 0.4 mm above a mirror. Interference fringes are observed on a screen 6 m away, and the interface is between the light coming from the source and the light...
  21. K

    Synthesis question Hurray

    I don't really need a full walkthrough, but if any you you guys spot a product/reagent 1-19 that you notice is right or wrong then please let me know :)
  22. K

    Chemistry problems (help please)

    2.) Which of the following are redox reactions? a.) 2Na + 2H2O ---> 2NaOH + H2 I can't really explain what they are better than your book or teacher. But, I know that working and seeing examples can help a lot. Check out a) 2Na+ + H2 + 2OH- = 2Na + 2H2O Do the questions over and over...
  23. K

    What is the chemical name for:

    also, the fact that it's dissolved in an alcohol means you might be trying to oxidize a molecule that doesn't dissolve in water. The solvent doesn't really matter, as far as reactions go. You just got to rmemember which solvents are polar protic, aprotic, and nonpolar :)
  24. K

    What is the chemical name for:

    I don't know about oyster shell, but: cobalt(II) oxide Could be a Co atom having a +2 charge which will join an O atom having a -2 charge. cobalt(III) oxide would have 2 Co atoms each with a charge of -3 surrounded by 3 O atoms each with a -2 charge. In each case, the O atoms maintin their...
  25. K

    Aerospace Engineeering Assignment

    One cool airfoil diagram is the one that explains why birds fly in a V: http://www.warren-wilson.edu/~physics/PhysPhotOfWeek/20060929GeeseV/index.html" [Broken] It means the lead bird and the 2 flanking birds do extra work, but the everage of each bird's total work is reduced by a huge...
  26. K

    Synthesis question Hurray

    I numbered each reagent and product so you can point and laugh accurately. Any tips would be awesome!
  27. K

    Mirror reflection question

    So was that a typo? Test tomorrow...
  28. K

    Mirror reflection question

    I'm studying for a test that is going to cover mirrors and lenses. I was under the impression that the focal length for any concave or convex mirror was half the radius of curvature: f=r/2 but one of the questions in my book involving a convex mirror uses a different value for f, according...
  29. K

    Equivalent Capacitance question

    That does make sense! Thanks
  30. K

    Equivalent Capacitance question

    I have learned how to find equivalent capacitence when capacitors are in series and when they are in parallel, but I came across a problem where I'm confused about the capacitors: Normally I first find equivalent capacitence of parallel capacitors by adding them together. Then use the...
  31. K

    Torque and tension question

    Actually, I got the lever arm on tension messed up there. Looks like the lever arm of tension is actually (0.414)(x_strut)Sin(30) This fix yields a tension of 11816 N of tension in the wire
  32. K

    Torque and tension question

    You guys are about 10x as helpful as my teacher! Here is where I have gotten: Grav Torques from the masses + Torque from wire's tension = 0, so: x_strut is distance from P to the 500lb mass lever arm x_wire is distance from where the wire is grounded to P h is the height of where the wire and...
  33. K

    Torque and tension question

    The net torque at P has to be zero. I guess my problem is that I haven't figured out how to numerically describe the positions of the forces relative to P. For instance, one of the torque forces is the 500 lb weight. I know the direction of the force is straight down, but I'm not sure how to...
  34. K

    Torque and tension question

    The picture I attached to this thread is a system that I came across while studying for my final exam today. It is a system that is in equilibrium, and the only numerical values are: Angle of wire/ground: 30 Angle of strut/ground: 45 Mass of hanging weight: 500 lb Mass of strut: 100 lb...
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